Material for organic electroluminescence device and method for producing the same

ABSTRACT

An organic electroluminescence device material having emission centers is formed by bringing a source ( 1 ) containing an emission center-forming compound absorptive of laser beams into contact with a target ( 2 ) having at least one function selected from an electron-transporting function and a hole-transporting function, and irradiating a laser beam at an intensity of or below the ablation threshold value of the source ( 1 ) from the source ( 1 ) side (or the target ( 2 ) side) thereby to implant the emission center-forming compound ( 3 ) of the source ( 1 ) into the target ( 2 ). Thus, it is possible to make a fine and minute pattern on the organic electroluminescence device material.

This application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/JP99/04668 which has an Internationalfiling date of Aug. 27, 1999, which designated the United States ofAmerica.

TECHNICAL FIELD

The present invention relates to a process for producing a material fororganic electroluminescence device by implanting or injecting anemission center-forming compound through molecular implantation withlaser, a material for organic electroluminesdence device obtained bythis process, and to an organic electroluminescence device (elements)produced with this organic electroluminescence device material.

BACKGROUND TECHNOLOGY

Electroluminescence devices (hereinafter, sometimes referred to simplyas EL devices) have generally been classified as inorganic EL devices ororganic EL devices according to what they are made from. On one handsome inorganic EL devices utilizing inorganic fluorescent molecules arealready in practical use, and have been brought into application to thebacklight of clocks or the like, while on the other hand organic ELdevices have been desired to be brought into practical use because oftheir excellence in brightness or luminance, efficiency, and high-speedresponsivity.

Electroluminescence devices are made from a compound or compounds havingan electron-transporting function, a hole-transporting function, and anemission center-forming function. As for their structures, there havebeen reported devices of the single-layer type having a single layerprovided with all the functions mentioned above, and devices of themultilayer-type composed of layers having different functions. Theprinciple of light emission is considered to be based on the phenomenonthat electrons or holes injected from a pair of electrodes recombinewithin a light-emitting layer to form excitons, which excite themolecules of a light emissive material for the light-emitting layer.

As a compound constituting each layer, a low-molecular weight compoundof high light-emission efficiency, a macromolecular compound having highphysical strength, or the like is employed. However, when alow-molecular weight compound is used, a film is formed by means of avapor deposition technique which is inferior in productivity, while amacromolecular compound is formed into a film by coating or applying asolution and thus capable of being formed into films of larger sizes.

Japanese Patent Application Laid-Open No. 96959/1996 (JP-A-8-96959) andJapanese Patent Application Laid-Open No. 63770/1997 (JP-A-9-63770)disclose organic EL devices comprising a single light-emitting layermade of a polymer binder within which varieties of fluorescent dyes (orcolorants, pigments) are dispersed, the polymer binder having bothelectron-transporting function and hole-transporting function. Each ofthese organic EL devises is reported to present, as a whole, white lightdue to the light emission of each light-emitting compound independent ofone another. Moreover, as compared with organic EL devices of themultilayer-type, those of the single-layer type are hardly deterioratedin light-emission intensity.

Fine patterning, particularly multicolor patterning (full-coloration) ofthese organic EL devices is difficult because, in their fabrication, afilm is formed by means of a solution coating technique in which asolution of a polymer binder and a fluorescent dye(s) dispersed in aspecific solvent is applied onto a substrate.

As multicolor patterning methods, a color filer method, acolor-converting method, the ink-jet method by T. R. Hebner (Appl. Phys.Lett. 72,5 (1998), p.519), the photobleaching method by Kido, et al, andothers have been reported.

The color filter method or color-converting method has the advantage ofnot requiring the patterning of a light-emitting layer, but suffersdeterioration in conversion efficiency caused by the use of a filter. Inthe ink-jet method, a pattern formed by ink-jet printing shows acenter-raised, i.e., conical profile and is inferior in smoothness ofits surface, resulting in difficulty in uniformly providing electrodesthereon. Moreover, the cross section of the pattern is desired to berectangular, but that of a pattern by ink-jet printing cannot be formedso and is circular. Further, the dimensions of a pattern largely dependson conditions under which the pattern is dried and the concentration ofthe solution. In the photobleaching method, only a special emissioncenter-forming compound which loses its fluorescence upon UV oxidationis employable and therefore colors expressable by EL devices arelimited.

As was described above, in conventional film-forming methods by solutioncoating, although it is possible to use a macromolecular compound ofhigh physical strength, it is difficult to provide fine patterns. Inaddition to that, also in the above-described patterning methods,compounds available for these methods are limited, and films havingsurface smoothness suitable for organic EL devices cannot be obtained.

As the molecular implantation technique, Japanese Patent ApplicationLaid-Open No. 297457/1994 (JP-A-6-297457) discloses a method comprisinga step of, with (A) a functional material or a solid material containinga functional material and (B) a solid material into which a functionalcomponent is to be implanted placed such as to face each other,irradiating a laser pulse thereby to implant the functional componentinto the solid material. Japanese Patent Application Laid-Open No.106006/1996 (JP-A-8-106006) discloses a method comprising the steps ofbringing a source film of an organic macromolecular compound withinwhich dyes absorptive of a pulse laser are dispersed into tight contactwith a target film of an organic macromolecular compound transmittableof a pulse laser, and irradiating a pulse laser from the target filmside at an intensity of or below the ablation threshold value of thesource film thereby to implant the dyes into the target film. Thisliterature says that the molecular implantation technique can beutilized in the fabrication of color filters for displays or the like.

Accordingly, an object of the present invention is to provide a materialfor organic EL device (particularly, organic EL device-use films) thatcan be fine-patterned even when a macromolecular compound is used as anEL device material, and a process for producing the same.

Another object of the present invention is to provide a material fororganic EL device which is excellent in surface smoothness and has goodcontactness with electrodes, and an organic EL device using the same.

DISCLOSURE OF THE INVENTION

The inventors of the present invention made intensive and extensivestudies to achieve the above objects, and finally found that a molecularimplantation technique using a laser makes it possible to implant anemission center-forming compound(s) with ease even in the case ofinjection into a macromolecular compound, and provide organic EL devicesthat can be finely and minutely patterned.

That is, the production process of a material for organic EL device ofthe present invention comprises the steps of

bringing a source (A) containing an emission center-forming compoundabsorptive of a laser beam into contact with a target (B) which istransmittable of the laser beam and has at least one function selectedfrom an electron-transporting function and a hole-transporting function,and

irradiating the laser beam from the source (A) side or the target (B)side at an intensity of or below the ablation threshold (value) of thesource (A) thereby to implant the emission center-forming compound intothe target (B), providing a material for organic electroluminescencedevice having luminescence (emission) centers. The target may be anorganic polymer having at least one function selected from theelectron-transporting function and the hole-transporting function (e.g.,poly-N-vinylcarbazol) or may comprise a compound having at least onefunction selected from the electron-transporting function and thehole-transporting function and an organic polymer having film-formingproperties or film-formability.

The organic EL device material may be in the form of a film, and thelaser beam may be a pulse laser beam (pulsed laser) having a pulse widthof 10 Ps to 10 μs. The laser beam diameter may be 1 μm to 5 mm.

The present invention includes a material for organic EL device obtainedin accordance with the process described above, and an organic EL device(element) formed with this organic EL device material.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view showing a technique for implanting orinjecting an emission center-forming compound.

FIG. 2 is a schematic sectional view showing one embodiment(single-layer structure) of the organic electroluminescence device ofthe present invention.

FIG. 3 is a schematic sectional view showing another embodiment(multilayer structure) of the organic electroluminescence device of thepresent invention.

FIG. 4 is a schematic sectional view showing still another embodiment(multilayer structure) of the organic electroluminescence device of thepresent invention.

FIG. 5 is a schematic sectional view showing another embodiment(multilayer structure) of the organic electroluminescence device of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The source (A) and the target (B) in the present invention can be usedin any form and there is no particular restriction, but they are usuallyused in the form of films.

[Source (A)]

The source need only be capable of containing an emission center-formingcompound, and its production process is not particularly restricted. Thesource comprises, for example, an emission center-forming compound and avariety of organic polymers (e.g., thermoplastic resins, thermosettingresins). As the organic polymer, usually, use can be made of resinshaving film-forming properties (or film-formability).

Thermoplastic resins include olefinic resins such as polyethylene,polypropylene, ethylene-propylene copolymer, and polybutene; styrenicresins such as polystyrene, rubber-modified polystyrene (HIPS),acrylonitrile-styrene copolymer, and acrylonitrile-butadiene-styrenecopolymer; acrylic resins exemplified by homo- or copolymers of(meth)acrylic monomers, such as polymethyl methacrylate, copolymers of(meth)acrylates and copolymerizable monomers, such as methylmethacrylate-styrene copolymer, and polyacrylonitrile; vinyl-seriesresins exemplified by vinyl alcohol-series polymers, such as polyvinylalcohol and ethylene-vinyl alcohol copolymer, polyvinyl chloride, vinylchloride-vinyl acetate copolymer, polyvinylidene chloride, polyvinylacetate, ethylene-vinyl acetate copolymer; polyamide-series resins suchas 6-nylon, 6,6-nylon, 6,10-nylon, 6,12-nylon; polyester-series resinssuch as polyalkylene terephthalates (e.g., polyethylene terephthalate,polybutylene terephthalate), polyalkylene naphthalates; fluororesins;polycarbonates; polyacetals; polyphenylene ether; polyphenelene sulfide;polyethersulfone; polyether ketone; thermoplastic polyimide;thermoplastic polyurethane; and norbornene-series polymers.

Included among the thermosetting resins are phenolic resins, urearesins, meramine resins, thermosetting acrylic resins, unsaturatedpolyester resins, alkyd resins, diallyl phthalate resins, epoxy resins,and silicone resins.

These macromolecular compounds may be used either singly or incombination.

[Emission Center-forming Compound]

The luminescence (emission) center-forming compound need only be acompound having functions that qualify the compound as an emissioncenter-forming compound for organic El devices and absorptive of laserbeams, example of which are heterocyclic compounds containing at leastone hetero atom selected from oxygen atom, nitrogen atom and sulfuratom, such as 2,5-bis (5-tert-butyl-2-benzoxazoyle)-thiophene, nile red,coumarins typified by coumarin 6 and coumarin7,4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran, andquinacridone; condensed polycyclic hydrocarbons such as rubrene andperylene; 1,1,4,4-tetraphenyl-1,3-butadiene (TPB),1,4-bis(2-(4-ethylphenyl)ethynyl)benzene, and4.4′-bis(2,2′-diphenylvinyl)biphenyl, with nile red and coumarin 6particularly preferred.

The structures of nile red and coumarin 6 are shown below:

The wavelength of light emitted by nile red is 580 nm (emission of redlight) and that of coumarin 6 is 490 nm (emission of green light).

These emission center-forming compound may be used either singly or incombination.

The proportion of the emission center-forming compound contained in thesource (A) is not particularly limited, and is, e.g., about 0.1 to 30parts by weight, preferably about 1 to 25 parts by weight, and morepreferably about 3 to 20 parts by weight relative to 100 parts by weightof the source.

[Target (B)]

Insofar as the target is transmittable of laser beams and has at leastone function selected from the electron-transporting and thehole-transporting function, there is no particular restriction inrespect of the material forming the target, and the target may be (I) aresin (organic polymer) having at least one function selected from theelectron-transporting function and the hole-transporting function, or(II) a resin material which originally has neither theelectron-transporting function nor the hole-transporting function but towhich the electron-transporting function and the hole-transportingfunction may be given. As the resins (I) and (II), resins having film-or coat-forming properties are preferable (organic polymers).

As the resin (I) having at least one function selected from theelectron-transporting function and the hole-transporting function, theremay be exemplified polyphenylenevinylenes such as polyphenylenevinylene,poly-2,5-dimethoxyphenylenevinylene, and polynaphthalenevinylene;polyphenylenes (particularly, polyparaphenylene) such aspolyparaphenylene and poly-2,5-dimethoxyparaphenylene;polyalkylthiophenes such as poly(3-alkylthiophene);polycycloalkylthiophenes such as poly(3-cyclohexylthiophene);polyarylthiophenes such as poly(3-(4-n-phexylphenyl)thiophene;polyfluorenes such as polyalkylfluorene; vinyl-series polymers having atleast one functional group selected from hole-transporting functionalgroups and electron-transporting functional groups in the main chain orside chain, such as poly-N-vinylcarbazole (PVK),poly-4-N,N-diphenylaminostyrene,poly(N-(p-diphenylamino)phenylmethacrylamide),poly(N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diaminomethacrylamide)(PTPDMA), and poly-4-(5-naphthyl-1,3,4-oxadiazole)styrene;polymethylphenylsilane; polymers having an aromatic amine derivative inthe side or main chain; and copolymers thereof. These resins may be usedeither singly or in combination. Included among the preferred targetsare poly-N-vinylcarbazole having a hole-transporting function,copolymers containing N-vinylcarbazole as a main constituent, andaromatic amine derivatives.

PVK is amorphous and excellent in heat resistance (glass transitiontemperature Tg: 224° C.). The degree of polymerization of PVK is notparticularly restricted, and is, for example, about 200 to 200,000,preferably about 500 to 50,000.

Further, if needed, the electron-transporting function orhole-transporting function is given to the resin (I).

Examples of the compound having an electron-transporting function areoxadiazole derivatives such as2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD),2,5-bis(1-naphthyl)-1,3,4-oxadiazole (BND),1,3-bis[5-(4-tert-butylphenyl)-1,3,4-oxadiazole]benzene (BPOB),1,3,5-tris[5-(4-tert-butylphenyl)-1,3,4-oxadiazole]benzene (TPOB), and1,3,5-tris[5-(1-naphthyl)-1,3,4-oxadiazole]benzene (TNOB);diphenoquinones such as 3,5,3′,5′-tetrakis-tert-butyldiphenoquinone;1,2,3,4,5-pentaphenyl-1,3-cyclopentadiene (PPCP); and quinolinic acidcomplexes such as tris(8-quinolinorato)aluminium (III) complex,bis(benzoquinolinorato)beryllium complex,tris(10-hydroxybenzo[h]quinolilate)beryllium complex, with PBDparticularly preferred.

As the compound having a hole-transporting function, there may beexemplified aromatic tertiary amines such asN,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD),N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4′-diamine (NPD),1,1-bis[(di-4-tolylamino)phenyl]cyclohexane,N,N,N′N′-tetra(3-methylphenyl)-1,3-diaminobenzene (PDA),4,4′,4″tris(3-methylphenylphenylamino)triphenylamine (m-MTDATA),4,4′,4″-tris(1-naphthylphenylamino)triphenylamine(1-TNATA),4,4′,4″-tris(2-naphthylphenylamino)triphenylamine (2-TNATA),4,4′,4″-tri(N-carbozolyl)triphenylamine (TCTA),1,3,5-tris[4-(3-methylphenylphenylamino)phenyl]benzene (m-MTDAPB), andtriphenylamine; and phthalocyanines.

These compounds can be used either singly or in combination.Incidentally, these can also be used as emission center-formingcompounds.

The proportion of the above-mentioned component contained in the resin(I) (e.g., PVK) can be selected from within the range not adverselyaffecting the functions qualifying the resin as an organic EL devicematerial, and is, for example, about 10 to 300 parts by weight andpreferably about 20 to 200 parts by weight relative to 100 parts byweight of the target.

When the target contains such component or components, an organic ELdevice which will later be described can be made such as to have asingle-layer structure, and the organic EL device so fabricated not onlyhas improved luminous efficiency but also is economically advantageous.

There is no specific restriction in respect of the resin (II), and sucha variety of organic polymers as exemplified in the section discussingthe source (e.g., thermoplastic resins, thermosetting resins) areavailable. At least one function selected from the electron-transportingfunction and the hole-transporting function may be given to theseresins. Exemplified as the compound(s) to be used are compounds similarto those enumerated above. Usually, use can be made of resins havingfilm- or coat-forming properties.

The amount of the compound having an electron-transporting orhole-transporting function to be added is about 10 to 300 parts byweight and preferably about 20 to 200 parts by weight relative to 100parts by weight of the resin (II).

The resin (I) and the resin (II) may be used in combination, and to amaterial of such combination may further be given at least one functionselected from the electron-transporting function and thehole-transporting function.

[Production Process of Organic EL Device Material (MolecularImplantation)]

The process for producing organic EL device materials of the presentinvention comprises the steps of bringing a source (A) into contact witha target (B) and irradiating a laser beam through the source (A) or thetarget (B) at an intensity of or below the ablation threshold value ofthe source (A) thereby to implant or inject the emission center-formingcompound into the target (B), providing an organic electroluminescencedevice material having luminescence centers. Films for organic EL deviceare usually produced using a source film and a target film.

Exemplified as the laser beam to be used in the present invention are,though it differs depending on the species of the emissioncenter-forming compound to be used, laser beams having an oscillationwavelength within the range of 190 to 1,100 nm. When using a pulse laserbeam (pulsed laser beam), the frequency is about 0.5 to 50 Hz andpreferably about 0.5 to 30 Hz. Moreover, although the pulse width variesdepending on the wavelength of the laser beam, it is 10 ps to 10 μs,preferably about 10 ps to 100 ns. The shorter the pulse width (duration)is, the less the decomposition of the emission center-forming compoundoccurs, and therefore, the emission center-forming compound is hardlydamaged.

Exemplified as the source of the laser beam are ArF excimer laser (193nm), KrF excimer laser (248 nm), XeCl excimer laser (308 nm), XeFexcimer laser (351 nm), nitrogen laser (337 nm), dye laser (nitrogenlaser, excimer laser, or YAG laser excitation, 300 to 1,000 nm),solid-state laser (Nd:YAG excitation, semiconductor laser excitation,etc.), ruby laser (694 nm), semiconductor laser (650 to 980 nm), tunablediode laser (630 to 1,550 nm), titanium-sapphire laser (Nd:YAGexcitation, 345 to 500 nm, 690 to 1,000 nm), and Nd:YAG laser (FHG: 266nm, THG: 354 nm, SHG: 532 nm, fundamental wave: 1,064 nm).

In the production process of the present invention, it is important toirradiate a laser beam at an intensity of or below the ablationthreshold of the source film (A). Irradiation of a laser beam at anintensity of or below the ablation threshold makes it possible toeffectively implant the emission center-forming compound contained inthe source film (A). Particularly, the amount of the emissioncenter-forming compound to be implanted can be controlled by regulating,e.g., the intensity and wavelength of the laser, and how many times thelaser beam is shot.

The ablation threshold of the source film (A) varies depending on thespecies of the compound forming the film and that of the emissioncenter-forming compound. Moreover, the ablation threshold also dependson the wavelength and pulse width of the laser beam. In the presentinvention, the ablation threshold is defined as follows.

The term “ablation threshold value” used in the present invention isdefined as a term referring to, assuming that a source film isirradiated with one shot of laser beam and observed by a contact-typesurface morphology measuring apparatus (e.g., DEKTAK3030ST, manufacturedby SLOAN), the lowest laser intensity (mJ/cm²) measured on the surfaceirradiated with the laser beam at which intensity the surface mightsuffer changes in surface conditions or morphology by a depth of 50 nmor more, the source and the laser being the same as those employed inthe present invention.

Hereinafter, the process of the present invention for producing amaterial for organic EL device (particularly, films for organic ELdevice) will be described with reference to Figures. FIG. 1 shows oneembodiment of the present invention. A source film (1), a target film(2), an emission center-forming compound (3), a substrate (4) for thetarget film side, and a substrate (5) for the source film side areillustrated therein.

Firstly, the target film (2) is interposed between the source film (1)and the substrate (4) such that the target film (2) is in contact withor intimate contact with the source film (1), and a laser beam isirradiated from the source film side at an intensity of or below theablation threshold of the source film (1). Usually, the laser beam isshot about 1 to 50 times, preferably about 1 to 25 times. Havingabsorbed the laser beam, the emission center-forming compound in thesource film obtains high translational energy and are injected orimplanted from the source film into the target film without beingdecomposed, and there is provided a film for organic EL device.

The laser beam may be irradiated from the target film side.

The substrate that is used need only be transparent, and examples ofwhich are plates of glass, such as soda glass, alkali-free glass andquartz glass, or polymer sheets or films of polyesters, polysulfonse, orpolyethersulfones. In the case of fabrication of flexible organic ELdevices, polymer films are preferred.

In the process of the present invention for producing a material fororganic EL device, fine and minute patterning can be realized bysuitably regulating the laser beam diameter according to the intendedapplication. The beam diameter is not particularly limited, and is forexample about 1 μm to 5 mm, preferably about 10 μm to 1 mm. Moreover,when irradiating the laser beam through a photomask, the photomask makesit possible to freely design not only the size but also theconfiguration of the pattern. Furthermore, at-a-time patterning overlarger areas is made possible by using a photomask and increasing thediameter of the laser beam. Moreover, there may be used a plurality ofsources having emission center-forming compounds different from oneanother. For example, the use of sources containing emissioncenter-forming compounds of red, green, and blue makes the selection ofcolor easier. Thus, according to the present invention, a material fororganic EL device with a multicolor pattern of diversified configurationcan be obtained.

According to the production process of the present invention, theemission center-forming compound can be injected into the target not ina dispersed or spread state but step-like (i.e., the emissioncenter-forming compound is injected into the target by a uniform depth,showing a rectangular profile). The depth varies with the species of theemission center-forming compound or the target, or the laser intensity,and is for example about 10 nm to 300 nm, preferably about 15 nm to 200nm, and more preferably about 20 nm to 100 nm. Furthermore, it ispossible to implant only an emission center-forming compound withoutdeteriorating the smoothness of the surface of an organic EL devicematerial, for the irradiation is effected at an intensity of or belowthe ablation threshold.

[Organic Electroluminescence Device]

The organic electroluminescence device of the present inventioncomprises an organic EL device material obtained in accordance with theprocess described above (particularly, a light-emitting layerconstituted of a target film into which an emission center-formingcompound is injected) and a pair of electrodes.

As an anode, a transparent electrode formed by vacuum deposition orother methods (e.g., indium-tin-oxide (ITO) electrode) or the like isused, and a highly conductive metal having a small work function (e.g.,magnesium, lithium, aluminium, or silver) is used as a cathode. In thecase where magnesium is used as the cathode, the magnesium may becoevaporated (or co-deposited) with a small amount of silver (e.g., 1 to10% by weight) for improving the adhesion with an organic EL device-usefilm.

When the light-emitting layer has both the electron-transportingfunction and the hole-transporting function, the organic EL device ofthe present invention can be made such as to have a single-layerstructure. When the light-emitting layer is lacking in either theelectron-transporting function or the hole-transporting function or whenattempting to improve each function, a layer having the desired functionmay be laminated on the light-emitting layer by a conventional vapordeposition technique or a solution coating technique. These layers maybe of low-molecular weight compounds or macromolecular compounds, andeither will do. The organic EL device can take, for example, asingle-layer structure or a multilayer-structure as shown in FIGS. 2 to5.

That is, as illustrated in FIG. 2, the organic EL device may be onecomposed of a substrate (10), an anode (11) formed thereon, alight-emitting layer (12), and a cathode (13) laminated in this order,or, as shown in FIG. 3, it may be one composed of a substrate (20), ananode (21) formed thereon, a hole-transporting layer (24),light-emitting layer (22), and a cathode (23) laminated: in this order.Further, as shown in FIG. 4, the organic EL device may be one composedof a substrate (30), an anode (31) formed thereon, a light-emittinglayer (32), an electron-transporting layer (35), and a cathode (33)laminated in this order, or, as shown in FIG. 5, it may be one composedof a substrate (40), an anode (41) formed thereon, a hole-transportinglayer (44), a light-emitting layer (42), an electron-transporting layer(45), and a cathode (43) laminated in this order.

The thickness of each of the layers constituting the organic EL deviceis not particularly limited, and is about 100 to 10,000 Å(e.g., 100 to5,000 Å), preferably about 300 to 3,000 Å, and more preferably about 300to 2,000 Å. When films are used, the thickness of each film can beselected from within the ranges mentioned above.

According to the present invention, in fabricating organic EL devices,fine and multicolor patterning which had long been difficult to realizewas made possible. Further, since the organic EL device material(particularly, organic EL device-use films) of the present invention isexcellent in surface smoothness, it adheres to electrodes well, and theorganic EL device of the present invention is free from the irregularityin voltage caused upon application of voltage because of the emissioncenter-forming compound implanted step-like.

INDUSTRIAL APPLICABILITY

According to the present invention, since an emission center-formingcompound is implanted within a target by means of a molecularimplantation technique, fine and minute multicolor patterning ispossible even when a macromolecular compound is used.

Moreover, irradiation at an intensity of or below the ablation thresholdof a source makes it possible to uniformly implant the emissioncenter-forming compound without deteriorating the smoothness of anorganic EL device material. Thus, the use of the organic EL devicematerial of the present invention realizes better adhesion withelectrodes and uniform application of voltage.

EXAMPLES

Hereinafter, the present invention will be described in further detailbut should by no means be construed as defining the scope of theinvention.

Example 1

(Preparation of Source Film)

A source film of 2 μm thick was prepared by dissolving polybutylmethacrylate (Aldrich Chemical Company, Inc., molecular weight: 3.4×10⁵containing 5% by weight of coumarin 6 (Nippon Kankoh Shikiso, K.K.) inchlorobenzene and then applying the resultant mixture onto a substrateof quartz by spin coating.

(Preparation of Target Film) On the one hand 500 mg ofpoly-N-vinylcarbazol having a hole-transporting function (PVK:manufactured by Kanto Kagaku, K.K.) and 500 mg of2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole having anelectron-transporting function (PBD: Aldrich Chemical Company, Inc.)were dissolved in 10 ml of 1,2-dichloroethane while on the other hand acoat layer of indium-tin-oxide (ITO) was formed on a glass substrate.The ITO substrate thus obtained was subjected to a dip coating using the1,2-dichloroethane solution to form, on the ITO coat layer, a targetfilm having the electron hole-transporting functions of 1,000 Å thick.

(Molecular Implantation)

A test piece, composed of the two films obtained above being in contactwith each other, was fabricated, and the test piece was irradiated withthird harmonic of YAG laser (wavelength: 355 nm, pulse width: 3ns,irradiation energy per unit area: 20 mJ/cm², diameter: 1.8 mm) ten times(ten shots) at a frequency of 1 Hz from the direction of the substrateadjoining the target film.

(Organic EL device)

An Al/Li electrode of 2,000 Å thick (manufactured by Kohjundo Kagaku,K.K.; Li content: 0.5% by weight) was formed on the molecular-implantedtarget film by vacuum deposition, providing an organic EL device.

With the ITO electrode of the organic EL device as an anode and theAl/Li electrode layer as a cathode, a direct electric field was appliedbetween the electrodes in the atmospheric air to cause the organic ELdevice to emit light. At a voltage of 18 V or so, emission of light wasbegan to be observed. There was observed the emission of blue light ofPVK from areas not implanted with molecules and of green light ofcoumarin 6 from areas implanted with molecules.

Example 2

(Preparation of Source Film)

A source film was obtained in the manner same as that in Example 1.

(Preparation of Target Film)

On one hand 150 mg ofN,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine havinga hole-transporting function (TPD: Tokyo Kasei K.K.), 300 mg of2-(4-biphenyl)-5-(4-tertbutylphenyl)-1,3,4-oxadiazole having anelectron-transporting function (PBD: Aldrich Chemical Company, Inc.),and 450 mg of polymethyl methacrylate as a binder polymer having nocarrier-transporting function (Aldrich Chemical Company, Inc.; PMMA)were dissolved in 30 mL of 1,2-dichloroethane, while on the other hand acoat of indium-tin-oxide (ITO) was formed on a glass substrate. The ITOsubstrate thus obtained was subjected to a dip coating using the1,2-dichloroethane solution to form, on the ITO coat, a target filmhaving the electron hole-transporting functions of 1,000 Å thick.

(Molecular Implantation)

A test piece, composed of the two films obtained above being in contactwith each other, was fabricated, and the test piece was irradiated withthird harmonic of YAG laser (wavelength: 355 m, pulse width: 3 ns,irradiation energy per unit area: 20 mJ/cm², diameter: 1.8 mm) ten times(ten shots) at a frequency of 1 Hz from the direction of the substrateadjoining the target film.

(Organic EL device)

An Al/Li electrode of 2,000 Å thick (manufactured by Kohjundo Kagaku,K.K.; Li content: 0.5% by weight) was formed on the molecular-implantedtarget film by vacuum deposition, providing an organic EL device.

With the ITO electrode of the organic EL device as an anode and theAl/Li electrode layer as a cathode, a direct electric field was appliedbetween the electrodes in the atmospheric air to cause the organic ELdevice to emit light. At a voltage of 15 V or so, emission of light wasbegan to be observed. There was observed the emission of blue light ofTPD from areas not implanted with molecules and of green light ofcoumarin 6 from areas not implanted with molecules.

Example 3

(Preparation of Source Film)

A source film was formed in the same manner as in Example 1.

(Preparation of Target Film)

A target film was formed in the same manner as in Example 2.

(Molecular Implantation)

A test piece, composed of the two films obtained above being in contactwith each other, was fabricated, and the test piece was irradiated withthird harmonic of YAG laser (wavelength: 355 nm, pulse width: 3 ns,irradiation energy per unit area: 20 mJ/cm², diameter: 1.8 mm) 20 times(20 shots) at a frequency of 1 Hz from the direction of the substrateadjoining the target film.

(Organic EL device)

An Al/Li electrode of 2,000 Å thick (manufactured by Kohjundo Kagaku,K.K.; Li content: 0.5% by weight) was formed on the molecular-implantedtarget film by vacuum deposition, providing an organic EL device.

With the ITO electrode of the organic EL device as an anode and theAl/Li electrode layer as a cathode, a direct electric field was appliedbetween the electrodes in the atmospheric air to cause the organic ELdevice to emit light. At a voltage of 15 V or so, emission of light wasbegan to be observed. There was observed the emission of blue light ofTPD from areas not implanted with molecules and of green light ofcoumarin 6 from areas implanted with molecules.

What is claimed is:
 1. A process for producing an organicelectro-luminescence device material having emission centers, whichcomprises: bringing a source (A) containing an emission center-formingcompound absorptive of a laser beam into contact with a target (B)having two sides, one of which is referred to as a source (A) side andone of which is referred to as a target (B) side, which target (B) istransmittable of a laser beam and has at least one function selectedfrom an electron-transporting function and a hole-transporting function,and irradiating a laser beam at an intensity of or below the ablationthreshold value of the source (A) from the source (A) side or from thetarget (B) side into said target (B), thereby to implant the emissioncenter-forming compound of the source (A) into the target (B) for theformation of a pattern and to form emission centers in the target (B).2. A process according to claim 1, wherein the organicelectroluminescence device material is a film.
 3. A process according toclaim 1, wherein the laser beam is a pulse laser beam.
 4. A processaccording to claim 3, wherein the pulse width of the pulse laser beam is10 ps to 10 μs.
 5. A process according to claim 1, wherein the diameterof the laser beam is 1 μm to 5 mm.
 6. A process according to claim 1 ,wherein the target is an organic polymer having at least one functionselected from the electron-transporting function and thehole-transporting function.
 7. A process according to claim 6, whereinthe organic polymer is a poly-N-vinylcarbazol or a copolymer comprisingN-vinylcarbazol as a main component.
 8. A process according to claim 1,wherein the target comprises a compound having at least one functionselected from the electron-transporting function and thehole-transporting function, and an organic polymer having film-formingproperties.
 9. A process according to claim 8, wherein the compound isat least one compound selected from the group consisting of oxadiazolederivatives having the electron-transporting function and aromatictertiary amines having the hole-transporting function.
 10. An organicelectroluminescence device material obtained by the process recited inclaim
 1. 11. An organic electroluminescence device material according toclaim 10, wherein the target is an organic polymer having at least onefunction selected from the electron-transporting function and thehole-transporting function.
 12. An organic electroluminescence devicewhich comprises a pair of electrodes and an organic electroluminescencedevice material recited in claim 10 which is interposed between theelectrodes.
 13. An organic electroluminescence device which comprises apair of electrodes and an organic electroluminescence device materialrecited in claim 10, which-is interposed between the electrodes, whereina single layer formed with an organic electroluminescence devicematerial recited in claim 10 is interposed between the pair ofelectrodes.